A. Algora and J. L. Tain

Instituto de Fisica Corpuscular, CSIC-Univ. de Valencia, Valencia

Spain

1. Introduction

The recent incidents at the Fukushima Daiichi nuclear power plant, following the great tsunami in Japan, have shown publicly, in a dramatic way, the need for a full knowledge and proper handling of the decay heat in reactors and spent-fuel pools.

In this chapter, after a short introduction to decay heat from the historical perspective we will discuss, how the decay heat is calculated from available nuclear data, and how the quality of the available beta decay data plays a key role in the accuracy and predictive power of the calculations. We will present how conventional beta decay experiments are performed and how the deduced information from such conventional measurements can suffer from the so-called pandemonium effect. Then we will introduce the total absorption technique, a technique that can be used in beta decay experiments to avoid the pandemonium effect. Finally, we will present the impact of some recent measurements using the total absorption technique, performed by an international collaboration that we lead on decay heat summation calculations and future perspectives.